Internet protocol (IP) telephony employs several protocols to setup and manage calls and other types of sessions. One of the most widely adopted protocols for IP-based signaling and communication sessions is the Session Initiation Protocol (SIP). SIP is used for initiating new calls, manipulating call paths, and enabling the association of services with users regardless of their point of connection in the network. For example, SIP allows multimedia and voice call sessions to be enabled, as well as other functions including call transfer, call termination, mid-call changes, endpoint determination, call forking, etc. The use of SIP as an interface assures that clients and servers in an IP telecommunication system can rely on a common and widely used method for exchanging information.
Many IP telephony systems support both analog private branch exchange devices (PBX) and digital devices (e.g., EPABX (Electronic Private Automatic Branch Exchange) devices). Due to the relative complexity in configuring devices for operation with an EAPBX, many users prefer analog PBXs. What is needed is automatic configuration of endpoint communication devices, such as SIP devices, with digital EAPBXs.